The reinforcing of supporting frameworks, for example, in the renovation of existing buildings by applying tension members made of fiber-reinforced plastic flat strip lamellas that are adhered under tension to the supporting framework, is known and can have advantages over reinforcing of supporting frameworks by steel constructions. Because the introduction of force into the tension members can take place via their end, anchoring on the tension sides of the supporting framework can be significant.
Different systems are known for the end anchoring but also for the pretensioning of tension members made of fiber-reinforced plastic flat strip lamellas including systems which can take into account the specifications when dealing with fiber-reinforced plastic flat strip lamellas.
For example, WO 2005/061813 A1 describes anchorings for tension members including two wedges and one anchor body which represents essentially a sleeve for the wedges, whereby a second, again wedge-shaped layer, is arranged between the wedges and the tension member. This second wedge-shaped layer includes a material with a lower modulus of elasticity than that of the first wedges and sleeve material and is arranged in the device in such a manner that the greatest thickness of this layer is provided in the area close to the load. This arrangement is for providing a uniform distribution of the contact pressure and of the shearing stress between the wedges and the tension member. The introduction of force into the tension member takes place in the described system via the sleeve (e.g., via the support of the sleeve on the supporting framework to be reinforced).
Devices described in WO 2005/061813 A1 can include wedges with different forms and materials used, as a result of which the manufacture of the device as well as its correct arrangement on a tension member can be associated with a higher cost.
The device of WO 2005/061813 also involves introduction of force into the tension member via the sleeve. As a result, the design of the device is basically limited in such a manner that the wedges have a reduction of cross-section in the direction of tension of the tension member because they can otherwise exit out of the sleeve upon loading.
WO 2004/003316 A1 describes a device for introducing force into tension members including substantially two wedges that are arranged around the tension member and are driven into a sleeve. The tension member is provided on its ends with means for imparting adhesion. The wedges include a highly rigid material.
The anchoring of tension members made of fiber-reinforced plastic flat strip lamellas by wedge anchorings uses a uniform distribution of stress in the boundary surface of the wedges and of the tension member in the longitudinal direction as well as in the transverse direction.
This distribution of stress can take place in an insufficient manner by the use of highly rigid material for the wedges, as they are described in WO 2004/003316 A1, as a result of which the efficiency of the introduction of force into the tension member can be limited. A balanced distribution of stress can be achieved in such an embodiment with great expense and high precision for the shaping of the wedges and their arrangement in the sleeve.